Stan Larson has proposed that here in the manuscripts we have an example of Oliver Cowdery first making a change in 𝓟, then transferring that change into 𝓞. See his discussion on pages 11–12 of “Textual Variants in Book of Mormon Manuscripts”, Dialogue: A Journal of Mormon Thought 10/4 (1977): 8–30. Larson argues that the original text read identically to what Oliver initially wrote in 𝓞:
Oliver corrected the text by supralinearly inserting the short if-clause “if ye have”, thus giving the final reading:
The transcript for this correction in 𝓞 reads as follows:
There is no apparent change in the level of ink flow for this supralinear insertion in 𝓞, although the ink for the insertion appears somewhat unevenly applied. The unevenness of the ink does suggest that the correction was made later when Oliver copied the text from 𝓞 into 𝓟.
The corresponding transcript for this correction in 𝓟 reads as follows (here I ignore the punctuation that John Gilbert, the 1830 typesetter, later added to 𝓟):
Here in 𝓟, the supralinear correction was written with somewhat heavier ink flow. Also note that in 𝓟, unlike 𝓞, Oliver first crossed out the two words how can, made the supralinear correction, and then continued inline by writing the entire question, “how can ye disbelieve on the Son of God”. It appears that Oliver redipped his quill just before making the supralinear correction (thus explaining why the ink level for the correction is somewhat heavier).
An alternative interpretation to Larson’s is that here in both manuscripts Oliver Cowdery made the same mistake twice. He didn’t expect two if-clauses in a row; so after writing the first if-clause, he skipped the second one and went directly to writing the question, “how can ye disbelieve on the Son of God”. In the original manuscript, he seems to have written the entire question before supralinearly inserting the second if-clause (“if ye have”). Perhaps the missing if-clause was noticed when Oliver read back the text to Joseph Smith. On the other hand, in the printer’s manuscript, Oliver had just started to write the how- question (writing only “how can”) when he made the correction. In this instance, Oliver seems to have simply made the same mistake a second time.
We can find evidence that sometimes Oliver Cowdery independently made the same error in both manuscripts, with each error being corrected immediately or virtually immediately at the time each manuscript was being written down. For a nearby example, see under Alma 32:36, where Oliver initially wrote “if the seed were good” in both 𝓞 and 𝓟; in each case, he virtually immediately corrected the were to was. As discussed under that passage, evidence elsewhere in the manuscripts supports was as the original reading in Alma 32:36.
In support of Larson’s hypothesis, there is evidence that Oliver Cowdery sometimes made the correction first in 𝓟, then corrected 𝓞 to agree with 𝓟. Here are two nearby examples of this kind of emendation: (1) in Alma 32:4, Oliver inserted an extra of after speaking (thus ending up with “of which we have been speaking of ”); (2) in Alma 34:4, Oliver changed heart to hearts in the original infinitival clause “as even to plant the word in your heart”. As described under these two passages, evidence elsewhere in the manuscripts argues against making these two emendations. Further, in both manuscripts, each of these emendations is distinctly secondary (with cramped and uneven writing and a different level of ink flow, especially in 𝓞).
Here in Alma 33:14, either reading (with or without “if ye have”) is theoretically possible. One important consideration is that the corrected text in this verse is supported by parallel language earlier in verses 12–13:
Note here, in particular, the ellipted form of this summarizing if-clause (“if ye do” rather than “if ye do believe those scriptures”). This usage in verse 13 argues that the corrected reading in verse 14 (the ellipted “if ye have”) is characteristic of Alma’s discourse style.
Moreover, instances of rhetorical summarizing of a preceding if-clause with a repeated but shortened form of that if-clause are scattered throughout the Book of Mormon, with examples from various individuals:
Internal evidence thus supports the repetition of the if-clause in Alma 33:14. The critical text will therefore accept the corrected reading in the manuscripts for this passage:
Since the initial reading without the second if-clause is a perfectly good reading, there would have been no motivation for Oliver Cowdery or Joseph Smith to have inserted this clause on their own. The critical text will therefore follow the corrected reading in 𝓞 and 𝓟, with its added if- clause (“if ye have”).
Summary: Maintain in Alma 33:14 the corrected reading in both manuscripts (“if ye have / how can ye disbelieve on the Son of God”); there is considerable evidence elsewhere in the text for the summarizing if- clause.